Ventilation control device, ventilation system, and program

ABSTRACT

In a ventilation control device, a ventilation-path setting unit is configured to set a ventilation path based on environmental information acquired by an information acquisition unit. A ventilation-quantity setting unit is configured to set a ventilation quantity based on the environmental information and the ventilation path. The ventilation-path setting unit sets a plurality of candidate paths having priorities in descending order of expected ventilation effects. In the case where a first candidate path having the highest priority is identical with a previously set ventilation path, the ventilation-path setting unit sets the first candidate path as the ventilation path, when a difference value between a room temperature previously acquired and a room temperature presently acquired is equal to or more than a threshold. The ventilation-path setting unit sets, as the ventilation path, a second candidate path having the second highest priority, when the difference value is less than the threshold.

TECHNICAL FIELD

The present invention relates to a ventilation control device, a ventilation system, and a program that are used to control ventilation in a building.

BACKGROUND ART

Conventionally, there has been known a system configured to allow wind to flow from the outside of the building to the inside of a building so that one or more persons existing in the building (hereinafter referred to as “one or more persons in rooms”) can live in a comfortable environment (for example, see JP 2012-122285 A, hereinafter referred to as “Document 1”).

The system described in Document 1 is configured to select a ventilation path in the building based on: information such as a wind direction and a wind speed outside the building, and outside air temperature; information such as room temperature inside the building; and information such as arrangement of rooms, and positions of openings.

However, the conventional system described in Document 1 has a problem that, when the difference between expected ventilation effect and actual ventilation effect is large, the conventional system selects a ventilation path having a small actual ventilation effect. That is, the conventional system described in Document 1 may select the ventilation path in which the actual ventilation effect is small although the expected ventilation effect is large.

SUMMARY OF INVENTION

The present invention has been made in the light of the above-mentioned problem, and it is an object thereof to provide a ventilation control device, a ventilation system, and program that can precisely set a ventilation path having a large actual ventilation effect.

A ventilation control device according to the present invention is configured, at predetermined intervals, to switch to a ventilation path in a building and a ventilation quantity of air passing through the switched ventilation path. The ventilation control device includes an information acquisition unit, a ventilation-path setting unit, a ventilation-quantity setting unit, and an output unit. The information acquisition unit is configured to acquire environmental information. The environmental information includes weather information and indoor environmental information. The weather information includes wind pertinent information, and air temperature and air humidity outside the building. The air temperature outside the building is an outside air temperature. The air humidity outside the building is an outside air humidity. The wind pertinent information is information about wind flowing outside the building. The indoor environmental information includes room temperature and room humidity in the building. The ventilation-path setting unit is configured to set the ventilation path based on the environmental information acquired by the information acquisition unit. The ventilation-quantity setting unit is configured to set the ventilation quantity based on the environmental information acquired by the information acquisition unit and the ventilation path that is set by the ventilation-path setting unit. The output unit is configured to output the ventilation path that is set by the ventilation-path setting unit and the ventilation quantity that is set by the ventilation-quantity setting unit. The ventilation-path setting unit is configured to set a plurality of candidate paths based on the environmental information. The plurality of candidate paths have priorities in descending order of expected ventilation effects. The ventilation-path setting unit is configured, in the case where a first candidate path having the highest priority of the plurality of candidate paths is identical with a previously set ventilation path, to set the first candidate path as the ventilation path, when a difference value between a room temperature previously acquired by the information acquisition unit and a room temperature presently acquired by the information acquisition unit is equal to or more than a predetermined threshold, and to set, as the ventilation path, a second candidate path having the second highest priority of the plurality of candidate paths, when the difference value is less than the predetermined threshold.

In the ventilation control device, the ventilation-path setting unit is preferably configured to always set the second candidate path as the ventilation path after the difference value in the first candidate path is less than the predetermined threshold predetermined times.

Preferably, the ventilation control device further includes an opening control unit. The opening control unit is configured to control an opening control device. The opening control device is configured to control opening/closing of an opening formed in the building, based on the ventilation path and the ventilation quantity that are output from the output unit.

Preferably, the ventilation control device further includes a state determining unit and an auxiliary-control unit. The state determining unit is configured to determine a state of a ventilation auxiliary device according to the ventilation path and the ventilation quantity that are output from the output unit. The ventilation auxiliary device is configured to assist ventilation through the ventilation path. The auxiliary-control unit is configured to control the ventilation auxiliary device so that the ventilation auxiliary device is in the state determined by the state determining unit.

Preferably, the ventilation control device further includes a first determining unit, a second determining unit, a third determining unit, and a switching-interval setting unit. The first determining unit is configured to determine whether or not a first absolute difference is less than a first specified value. The first absolute difference indicates an absolute difference between the room temperature and the outside air temperature that are acquired by the information acquisition unit. The second determining unit is configured, when the first absolute difference is less than the first specified value, to determine whether or not a second absolute difference is less than a second specified value. The second absolute difference indicates an absolute difference between the room temperature acquired by the information acquisition unit and a preset temperature in the ventilation path. The third determining unit is configured, when the second absolute difference is less than the second specified value, to determine whether or not a third absolute difference is less than a third specified value. The third absolute difference indicates an absolute difference between room temperature presently acquired by the information acquisition unit and room temperature previously acquired by the information acquisition unit. The switching-interval setting unit is configured to set each of the predetermined intervals to a first time period, when the first absolute difference is equal to or more than the first specified value, when the second absolute difference is equal to or more than the second specified value, or when the third absolute difference is equal to or more than the third specified value. The switching-interval setting unit is configured to set each of the predetermined intervals to a second time period longer than the first time period when the third absolute difference is less than the third specified value.

A ventilation system according to the present invention includes the ventilation control device and an opening control device. The opening control device is configured to control opening/closing of an opening of the building by control of the ventilation control device.

A program according to the present invention is used for, at predetermined switching intervals, switching to a ventilation path in a building and setting a ventilation quantity of air passing through the switched ventilation path. The program causes a computer to function as a ventilation-path setting unit, a ventilation-quantity setting unit, and an output unit. The ventilation-path setting unit is configured to set the ventilation path based on environmental information acquired by an information acquisition unit. The environmental information includes: wind pertinent information about wind flowing outside the building; weather information including air temperature and air humidity outside the building; and indoor environmental information including room temperature and room humidity in the building. The air temperature outside the building is an outside air temperature. The air humidity outside the building is an outside air humidity. The ventilation-quantity setting unit is configured to set the ventilation quantity based on the environmental information acquired by the information acquisition unit and the ventilation path that is set by the ventilation-path setting unit. The output unit is configured to output the ventilation path that is set by the ventilation-path setting unit and the ventilation quantity that is set by the ventilation-quantity setting unit. The program causes the computer, as the ventilation-path setting unit, to set a plurality of candidate paths based on the environmental information. The plurality of candidate paths have priorities in descending order of expected ventilation effects. The program causes the computer, as the ventilation-path setting unit, to set, in the case where a first candidate path having the highest priority of the plurality of candidate paths is identical with a previously set ventilation path, the first candidate path as the ventilation path, when a difference value between a room temperature previously acquired by the information acquisition unit and a room temperature presently acquired by the information acquisition unit is equal to or more than a predetermined threshold. The program causes the computer, as the ventilation-path setting unit, to set, as the ventilation path, a second candidate path having the second highest priority of the plurality of candidate paths, when the difference value is less than the predetermined threshold. The present invention is not limited to the program. The present invention may be a computer-readable recording medium recording the program.

According to the present invention, it is possible to precisely set the ventilation path having the large actual ventilation effect.

BRIEF DESCRIPTION OF DRAWINGS

Preferred embodiments of the present invention will now be described in further details. Other features and advantages of the present invention will become better understood with regard to the following detailed description and accompanying drawings where:

FIG. 1 is a block diagram showing a configuration of a ventilation control device according to an embodiment;

FIG. 2 is a block diagram showing a configuration of a ventilation system according to the embodiment;

FIG. 3 is a flow chart showing an operation of the ventilation control device according to the embodiment; and

FIG. 4 is a flow chart showing a setting-operation of a ventilation path of the ventilation control device according to the embodiment.

DESCRIPTION OF EMBODIMENTS

In a ventilation system according to an embodiment described below, a ventilation control device is configured to set a ventilation state (ventilation path, ventilation quantity) in a building at predetermined intervals (switching intervals).

When setting the ventilation path, first, the ventilation control device is configured to set a plurality of candidate paths having priorities in descending order of expected ventilation effects. Second, in the case where a first candidate path having the highest priority is identical with a previously set ventilation path, the ventilation control device is configured to set, as the ventilation path, not a first candidate path but a second candidate path having the second highest priority coming after that of the first candidate path, when a difference value between a previous room temperature and a present room temperature is less than a threshold.

That is, when the present room temperature is substantially equal to the previous room temperature, the ventilation control device according to the present embodiment is configured to determine that actual ventilation effect of the previously set ventilation path is small and to prevent the ventilation path having the small ventilation effect from being set continuously.

In the present embodiment, the ventilation path is set so that air passes through a space (room, passage, stairs, for example) in the building from the outside of the building. The ventilation quantity is the quantity of the air that passes through the ventilation path.

In the present embodiment, the high ventilation effect means that one or more persons in the building can feel comfort by the ventilation. Specifically, first, in the case where a difference between a room temperature before the ventilation and a room temperature after the ventilation is large, it is said that the ventilation effect is high. In this case, there is a theory that it should be considered that the case is preferable, in which the room temperature before the ventilation is higher than one or more persons' body temperature in the building and the room temperature after the ventilation decreases a temperature near the body temperature. Second, in the case where one or more persons' effective temperature in the building decreases, after the ventilation, from a high temperature at which one or more persons in the building is uncomfortable, it is said that the ventilation effect is high. Third, in the case where room concentration of carbon dioxide decreases, after the ventilation, from a very high state in which one or more persons in the building is unconformable, it is said that the ventilation effect is high. The inventors consider that the ventilation effect is high if any of these three cases occurs. On the other hand, if any one of these three cases does not occur, the ventilation effect is low. The low ventilation path means that no one in the building can feel comfort by the ventilation. Specifically, in the case where the difference between the room temperature before the ventilation and the room temperature after the ventilation is small and one or more persons' effective temperature in the building does not decrease and carbon dioxide in room(s) maintains a high state in which one or more persons in the building is uncomfortable does not decrease, it is said that the ventilation effect is low.

Hereinafter, the ventilation system according to the present embodiment will be described in detail with reference to drawings.

As shown in FIG. 2, the ventilation system according to the present embodiment includes a ventilation control device 1, a plurality of opening control devices 2, and a plurality of ventilation auxiliary devices 3. The ventilation system further includes an anemometer 4, a first thermo-hygrometer 5, a second thermo-hygrometer 6, and an input device 7.

Hereinafter, although the case where the ventilation system is used for the common single house will be described as an example, the ventilation system may be used not only for the single house but also for each dwelling unit in a collective housing for example. The ventilation system may be used for an office, a store, an institution, a factory, or the like.

Each opening control device 2 is configured to control opening/closing of an opening 81 formed in a building 8. Each opening control device 2 is a window opening/closing device configured to open/close a window as the opening 81 by operating a fitting (window glass, window shutter, or the like), for example, or a door opening/closing device configured to open/close an entrance as the opening 81 by operating a door. Examples of the door include an entrance door disposed at an entrance and a door disposed in the building 8. Each opening control device 2 is controlled by the ventilation control device 1.

The anemometer 4 is installed outside the building 8. The anemometer 4 is configured to measure a direction (wind direction) and a speed (wind speed) of wind flowing outside the building 8.

The first thermo-hygrometer 5 is installed outside the building 8. The first thermo-hygrometer 5 is configured to measure air temperature outside the building 8 (outside air temperature) and humidity outside the building 8 (outside air humidity).

The second thermo-hygrometer 6 is installed in the building 8. The second thermo-hygrometer 6 is configured to measure air temperature in the building 8 (room temperature) and humidity in the building 8 (room humidity).

The input device 7 is used, for example, for one person or any one of more persons in the building 8 (hereinafter “one or more persons in rooms”) inputting an instruction to the ventilation control device 1. The input device 7 is configured to receive an input of the preset temperature (target temperature) in the building 8, for example, by an input operation by one or more persons in rooms. The input device 7 may be also configured to receive inputs of various instructions other than the preset temperature.

The ventilation control device 1 is a controller(s) that includes, as a main component, a computer(s) (including a microcomputer(s)) in which a CPU(s) (Central Processing Unit(s)) and a memory(-ies) are mounted, for example. As shown in FIG. 1, the ventilation control device 1 includes an information acquisition unit 11, a preset-temperature acquisition unit 12, a storage unit 13, and an arithmetic processor 14.

The information acquisition unit 11 is configured to acquire environmental information (environment data). The environmental information (environment data) includes weather information (weather data) and indoor environmental information (indoor environment data). The weather information (weather data) includes wind pertinent information (wind permanent data), and air temperature and air humidity outside the building 8. The wind pertinent information is information about wind blowing outside the building 8, and includes a wind direction and wind speed of the wind. The indoor environmental information includes room temperature and room humidity in the building 8.

The information acquisition unit 11 includes a first acquisition unit (wind-pertinent-information acquisition unit) 111, a second acquisition unit (outside-air-temperature-and-humidity acquisition unit) 112, and a third acquisition unit (room-temperature-and-humidity acquisition unit) 113.

The first acquisition unit 111 includes an interface unit (not shown) for connecting with the anemometer 4. The first acquisition unit 111 is configured to acquire a measuring result of the anemometer 4, which is connected to the interface unit, from the anemometer 4. For example, the first acquisition unit 111 is configured to acquire the measuring result from the anemometer 4 at a cycle shorter than the switching interval for setting the ventilation state. Then, the first acquisition unit 111 is configured to select a wind direction based on the highest frequency from distribution of the wind directions acquired during the cycle (time period) from the time point when the previous ventilation state was set. The first acquisition unit 111 is configured to calculate an average value of wind speeds acquired during the cycle (time period) from the time point when the previous ventilation path and the previous ventilation quantity were set. Therefore, the first acquisition unit 111 can acquire, as the wind pertinent information, the selected wind direction and the calculated wind speed (average value). The first acquisition unit 111 may acquire the wind pertinent information from the anemometer 4 by wireless communication through a transmission medium of an electric wave instead of a cable.

The second acquisition unit 112 includes an interface unit (not shown) for connecting with the first thermo-hygrometer 5. The second acquisition unit 112 is configured to acquire a measuring result of the first thermo-hygrometer 5, which is connected to the interface unit, from the first thermo-hygrometer 5. That is, the second acquisition unit 112 is configured to acquire an outside air temperature and an outside air humidity from the first thermo-hygrometer 5. The second acquisition unit 112 may acquire the outside air temperature and the outside air humidity from the first thermo-hygrometer 5 by wireless communication through a transmission medium of an electric wave instead of a cable.

The third acquisition unit 113 includes an interface unit (not shown) for connecting with the second thermo-hygrometer 6. The third acquisition unit 113 is configured to acquire a measuring result of the second thermo-hygrometer 6, which is connected to the interface unit, from the second thermo-hygrometer 6. That is, the third acquisition unit 113 is configured to acquire indoor environmental information from the second thermo-hygrometer 6. The third acquisition unit 113 may acquire the indoor environmental information from the second thermo-hygrometer 6 by wireless communication through a transmission medium of an electric wave instead of a cable.

The preset-temperature acquisition unit 12 includes an interface unit (not shown) for connecting with the input device 7. The preset-temperature acquisition unit 12 is configured to acquire the preset temperature inputted by an input operation to the input device 7, which is connected to the interface unit, from the input device 7. The preset-temperature acquisition unit 12 may acquire the preset temperature from the input device 7 by wireless communication through a transmission medium of an electric wave instead of a cable.

The storage unit 13 includes a first storage unit (weather-information-history storage unit) 131, a second storage unit (indoor-environmental-information-history storage unit) 132, and a third storage unit (control-log storage unit) 133.

The first storage unit 131 is configured to store a history of the wind pertinent information that has been ever acquired by the first acquisition unit 111. Whenever the first acquisition unit 111 acquires the wind pertinent information, the wind pertinent information is stored in the first storage unit 131 by control of the arithmetic processor 14 so as to be associated with an acquisition date and an acquisition time. The first storage unit 131 is configured to store a history of the outside air temperature and the outside air humidity that have ever been acquired by the second acquisition unit 112. Whenever the second acquisition unit 112 acquires the outside air temperature and the outside air humidity, the outside air temperature and the outside air humidity are stored in the first storage unit 131 by control of the arithmetic processor 14 so as to be associated with an acquisition date and an acquisition time.

The second storage unit 132 is configured to store a history of the indoor environmental information that has been ever acquired by the third acquisition unit 113. Whenever the third acquisition unit 113 acquires the indoor environmental information, the indoor environmental information is stored in the second storage unit 132 by control of the arithmetic processor 14 so as to be associated with an acquisition date and an acquisition time.

The third storage unit 133 is configured to store, by control of the arithmetic processor 14, a history of a control content, that is, the control log, to each opening control device 2. Whenever the opening control unit 144 of the arithmetic processor 14 controls each opening control device 2 according to the control content of each opening control device 2, the control content is stored in the third storage unit 133 by control of the arithmetic processor 14 so as to be associated with a control date and a control time.

The arithmetic processor 14 includes a ventilation-path setting unit 141, a ventilation-quantity setting unit 142, an output unit 143, and an opening control unit 144. The arithmetic processor 14 further includes a state determining unit 145, and an auxiliary-control unit 146. The arithmetic processor 14 further includes a first determining unit 151, a second determining unit 152, a third determining unit 153, and a switching-interval setting unit 154. The arithmetic processor 14 can execute various programs to perform various processes. The various programs are stored in the storage unit 13.

The ventilation-path setting unit 141 is configured to set the ventilation path in the building 8 based on the environmental information acquired by the information acquisition unit 11 and the history information stored in the storage unit 13. The ventilation-path setting unit 141 of the present embodiment is configured to set the ventilation path in the building 8 by executing a ventilation-path setting program for setting the ventilation path. When the ventilation-path setting program is executed, building information about room arrangement (including a position of an opening 81) in the building 8 is preliminarily input in the storage unit 13. The ventilation-path setting program is stored in the storage unit 13.

The ventilation-quantity setting unit 142 is configured to set the ventilation quantity of air that passes through the ventilation path that is set by the ventilation-path setting unit 141, based on the environmental information acquired by the information acquisition unit 11, the ventilation path that is set by the ventilation-path setting unit 141, and the history information stored in the storage unit 13. The ventilation-quantity setting unit 142 of the present embodiment is configured to set the ventilation quantity of the ventilation through the ventilation path by executing a ventilation-quantity setting program for setting the ventilation quantity. When the ventilation-quantity setting program is executed, the building information about the room arrangement (including the position of the opening 81) in the building 8 is preliminarily input. The ventilation-quantity setting program is stored in the storage unit 13. The ventilation-quantity setting unit 142 has a function as a timer configured to clock the switching-interval. The switching-interval period is a time period between the previous switch timing and the present switch timing. The switch timing is a predetermined time point within a predetermined time period from a time point when the ventilation path and the ventilation quantity are set. The predetermined time point includes a time point when the ventilation path and the ventilation quantity are set. That is, the predetermined time point may be the time point when the ventilation path and the ventilation quantity are set, and a specific time point within the predetermined time period from the time point when the ventilation path and the ventilation quantity are set. The timer is configured to clock an elapsed time period from the predetermined time point.

The output unit 143 is configured to output, to the opening control unit 144, the ventilation path that is set by the ventilation-path setting unit 141 and the ventilation quantity that is set by the ventilation-quantity setting unit 142.

The opening control unit 144 is configured to determine the control content of each opening control device 2 based on the ventilation path and ventilation quantity outputted from the output unit 143. The opening control unit 144 is configured to determine the control content of each opening control device 2 so that the ventilation path through which the air of the ventilation quantity passes may actually be formed in the building 8. Then, the opening control unit 144 is configured to control each opening control device 2 according to the control content.

In the arithmetic processor 14, the ventilation-path setting unit 141 is configured to execute the ventilation-path setting program to set the ventilation path by the following operations. First, the ventilation-path setting unit 141 sets the plurality of candidate paths having the priorities in descending order of the expected ventilation effects, based on the environmental information acquired by the information acquisition unit 11. Next, in the case where the first candidate path, which has the highest priority of the plurality of candidate paths, is identical with the previously set ventilation path, the ventilation-path setting unit 141 is configured to set the first candidate path as the ventilation path, when a difference value (T2−T1) between room temperature T2, which is previously acquired by the information acquisition unit 11, and a room temperature T1, which is presently acquired by the information acquisition unit 11 is equal to or more than a predetermined threshold δ1. On the other hand, in this case, the ventilation-path setting unit 141 is configured to set, as the ventilation path, the second candidate path having the second highest priority of the plurality of candidate paths when the difference value (T2−T1) is less than the threshold δ1.

After the difference value (T2−T1) has been ever less than the threshold δ1 a predetermined times about the first candidate path having the highest priority, the ventilation-path setting unit 141 of the present embodiment is configured to always set the second candidate path as the ventilation path.

Incidentally, when the sufficient ventilation quantity is not acquired with the ventilation path that is set by the ventilation-path setting unit 141, it is necessary to operate a plurality of ventilation auxiliary devices 3 to ventilate forcibly.

Examples of each ventilation auxiliary device 3 include a fan (ventilation fan 31, ceiling fan 32) and an air conditioner 33. Each ventilation auxiliary device 3 is configured to assist the ventilation through the ventilation path that is set by the ventilation-path setting unit 141. The ventilation fan 31 is disposed in, for example, a kitchen or a bathroom in the building 8. The ceiling fan 32 is disposed, for example, on a ceiling of a room or above stairs in the building 8. The air conditioner 33 is disposed in a room in the building 8.

The state determining unit 145 is configured to determine a state of each ventilation auxiliary device 3 according to the ventilation path and the ventilation quantity that are outputted from the output unit 143.

The auxiliary-control unit 146 is configured to control each ventilation auxiliary device 3 to be in the state of each ventilation auxiliary device 3, which is determined by the state determining unit 145. Each ventilation auxiliary device 3 is configured to work according to control of the auxiliary-control unit 146.

The third storage unit 133 of the present embodiment is configured to store not only the history of the control content of each opening control device 2 but also a history of the state of each ventilation auxiliary device 3. Whenever the auxiliary-control unit 146 controls each ventilation auxiliary device 3, the state of each ventilation auxiliary device 3 is stored in the third storage unit 133 by the control of the arithmetic processor 14 so as to be associated with a control date and a control time.

Incidentally, since the wind direction and the wind speed change every moment, the ventilation control device 1 needs to switch the ventilation state (ventilation path, ventilation quantity) according to change in the wind direction and the wind speed. The switching interval at which the ventilation control device 1 switches the ventilation state is about ten minutes.

However, if the ventilation state is switched at a short time period more than necessary, discomfort to one or more persons in rooms may increase. On the contrary, even if the switching interval of the ventilation state is long, the room temperature may not reach the preset temperature, or the room temperature may exceed the preset temperature, which may result in decreasing comfort to one or more persons in rooms.

Then, the ventilation control device 1 according to the present embodiment can switch the switching interval of the ventilation state (ventilation path, ventilation quantity) according to the following determination condition, without fixing the switching interval.

The first determining unit 151 is configured to compare the room temperature (present room temperature T1) and the outside air temperature (present outside air temperature T3) that have been acquired by the information acquisition unit 11. The first determining unit 151 is configured to determine whether or not an absolute difference (hereinafter referred to as a “first absolute difference”) |T1−T3| between the present room temperature T1 and the present outside air temperature T3 is less than a first specified value A1.

The second determining unit 152 is configured to compare the room temperature (present room temperature T1) acquired by the information acquisition unit 11 with the preset temperature T4 in the ventilation path when the first absolute difference |T1−T3| is less than the first specified value A1. The second determining unit 152 is configured to determine whether or not an absolute difference (hereinafter referred to as a “second absolute difference”) |T1−T4| between the present room temperature T1 and the preset temperature T4 is less than a second specified value A2.

The third determining unit 153 is configured to compare the room temperature (present room temperature T1) acquired by the information acquisition unit 11 with the previously acquired room temperature T2 stored in the second storage unit 132 when the second absolute difference |T1−T4| is less than the second specified value A2. The third determining unit 153 is configured to determine whether or not an absolute difference (hereinafter referred to as a “third absolute difference”) |T1−T2| between the present room temperature T1 and the previous room temperature T2 is less than a third specified value A3.

The switching-interval setting unit 154 is configured to set the switching interval, that is, a next control start timing, for the ventilation state (ventilation path, ventilation quantity). When the first absolute difference |T1−T2| is equal to or more than the first specified value A1, the switching-interval setting unit 154 is configured to set the switching interval to the first time period. That is, in this case, the switching-interval setting unit 154 will set a next switch timing after the first time period passes from the present switch timing. Also, when the second absolute difference |T1−T3| is equal to or more than the second specified value A2, the switching-interval setting unit 154 is configured to set the switching interval to the first time period. Further, when the third absolute difference |T1−T4| is equal to or more than the third default value A3, the switching-interval setting unit 154 is configured to set the switching interval to the first time period.

On the other hand, when the third absolute difference |T1−T4| is less than the third specified value A3, the switching-interval setting unit 154 is configured to set the switching interval to the second time period. That is, in this case, the switching-interval setting unit 154 will set the next switch timing after the second time period passes from the present switch timing. A time period longer than the first time period is employed as the second time period.

That is, the ventilation control device 1 is configured to comparatively shorten the switching interval when any of the first absolute difference |T1−T2|, the second absolute difference |T1−T3|, and the third absolute difference |T1−T4| is equal to or more than the specified value (first specified value A1, second specified value A2, third specified value A3). On the other hand, the ventilation control device 1 is configured to comparatively lengthen the switching interval when the first absolute difference |T1−T2|, the second absolute difference |T1−T3|, and the third absolute difference |T1−T4| are less than the specified values.

Incidentally, the storage unit 13 is configured to store not only the history of the weather information, the history of the indoor environmental information, and the control log, but also various kinds of information if necessary.

The storage unit 13 is configured to store a program for causing the ventilation control device (computer) 1 to perform various functions. That is, the storage unit 13 is configured to store a program(s) that causes the ventilation control device 1 to function as the ventilation-path setting unit 141, the ventilation-quantity setting unit 142, the output unit 143, the opening control unit 144, the state determining unit 145, the auxiliary-control unit 146, the first determining unit 151, the second determining unit 152, the third determining unit 153, and the switching-interval setting unit 154. The program is preliminarily stored in the storage unit 13 at the time of shipment of the ventilation control device 1. However, when the ventilation control device 1 acquires the program after the shipment, as an example of the technique with which the ventilation control device 1 acquires the program, there is a technique using a computer-readable recording medium that stores the program. In the case of the technique using the computer-readable recording medium, the ventilation control device 1 need only to include a reader (not shown) for reading data in the recording medium. Examples of the recording medium include an optical disc and a memory card. Examples of the reader include a drive device configured to read out information on the optical disc, and a memory card reader configured to read out information in the memory card. As another technique with which the ventilation control device 1 acquires the program, there is a technique with which the ventilation control device 1 downloads the program from another device (for example, server) through a network. In the case of the technique of downloading the program through the network, the ventilation control device 1 need only to have a communication function for communicating with the above-mentioned other device through the network.

Next, a ventilation control method with the ventilation control device 1 according to the present embodiment will be described with reference to FIG. 3. The ventilation control method is realized by executing the program stored in the storage unit 13 of the ventilation control device 1.

First, the information acquisition unit 11 acquires the environmental information (S1). Next, the ventilation-path setting unit 141 of the arithmetic processor 14 sets the ventilation path based on the environmental information acquired in step S1 and the history information stored in the storage unit 13 (S2).

Here, a setting-operation of the ventilation path will be described in detail with reference to FIG. 4. In step S2, the ventilation-path setting unit 141 sets the plurality of candidate paths having priorities in descending order of expected ventilation effect (S21).

When the first candidate path having the highest priority of the plurality of ventilation paths is not identical with the previously set ventilation path (NO at S22), the ventilation-path setting unit 141 sets the first candidate path as the ventilation path (S24).

On the other hand, in the case where the first candidate path is identical with the previously set ventilation path (YES at S22), the ventilation-path setting unit 141 sets the first candidate path as the ventilation path (S24), when the difference value (T2−T1) between the previous room temperature T2 and the present room temperature T1 is equal to or more than the threshold δ1 (NO at S23).

On the other hand, when the difference value (T2−T1) is less than the threshold δ1 (YES at S23), the ventilation-path setting unit 141 sets, as the ventilation path, the second candidate path having the second highest priority of the plurality of ventilation paths (S25).

As shown in FIG. 3, after step S2, the ventilation-quantity setting unit 142 of the arithmetic processor 14 sets the ventilation quantity based on the environmental information acquired in step S1, the ventilation path that is set in step S2, and the history information stored in the storage unit 13 (S3).

Then, the state determining unit 145 of the arithmetic processor 14 determines the state of each ventilation auxiliary device 3 according to the ventilation path that is set in step S2 and the ventilation quantity that is set in step S3 (S4). When the operation of each ventilation auxiliary device 3 is unnecessary, the state determining unit 145 determines the state of each ventilation auxiliary device 3 as an OFF state.

Then, the opening control unit 144 of the arithmetic processor 14 controls each opening control device 2 based on the ventilation path that is set in step S2 and the ventilation quantity that is set in step S3 (S5). The auxiliary-control unit 146 of the arithmetic processor 14 controls each ventilation auxiliary device 3 so as to be in the state determined in step S4.

Then, the first determining unit 151 determines whether or not the first absolute difference |T1−T2| is less than the first specified value A1 (S6). When the first absolute difference |T1−T2| is less than the first specified value A1 (YES at S6), the second determining unit 152 determines whether or not the second absolute difference |T1−T3| is less than the second specified value A2 (S7). When the second absolute difference |T1−T3| is less than the second specified value A2 (YES at S7), the third determining unit 153 determines whether or not the third absolute difference |T1−T4| is less than the third specified value A3 (S8).

In step S6, when the first absolute difference |T1−T2| is equal to or more than the first specified value A1 (NO at S6), the switching-interval setting unit 154 of the arithmetic processor 14 sets the switching interval to the first time period (S9). In step S7, when the second absolute difference |T1−T3| is also equal to or more than the second specified value A2 (NO at S7), the switching-interval setting unit 154 sets the switching interval to the first time period. When the third absolute difference |T1−T4| is also equal to or more than the third specified value A3 (NO at S8), the switching-interval setting unit 154 sets the switching interval to the first time period.

On the other hand, when the third absolute difference |T1−T4| is less than the third specified value A3 (YES at S8), the switching-interval setting unit 154 sets the switching interval to the second time period longer than the first time period (S10).

Then, in steps S2 and S3, after the first time period passes from the predetermined time point within the predetermined time period from the time point at which the ventilation path and the ventilation quantity are set (YES at S11), the ventilation control device 1 returns to step S1 and performs the operation for switching the ventilation state. Also, after the second time period passes from the predetermined time point (YES at 512), the ventilation control device 1 returns to step S1 and performs the operation for switching the ventilation state.

The ventilation control device 1 according to the present embodiment described above is configured, at the predetermined intervals, to switch to the ventilation path in the building 8 and to set the ventilation quantity of the air passing through the switched ventilation path. The ventilation control device 1 includes the information acquisition unit 11, the ventilation-path setting unit 141, the ventilation-quantity setting unit 142, and the output unit 143. The information acquisition unit 11 is configured to acquire the environmental information. The environmental information includes the weather information and the indoor environmental information. The weather information includes the wind pertinent information, and the air temperature and the air humidity outside the building 8. The air temperature outside the building 8 is the outside air temperature. The air humidity outside the building 8 is the outside air humidity. The wind pertinent information is information about the wind flowing outside the building 8. The indoor environmental information includes the room temperature and the room humidity in the building 8. The ventilation-path setting unit 141 is configured to set the ventilation path based on the environmental information acquired by the information acquisition unit 11. The ventilation-quantity setting unit 142 is configured to set the ventilation quantity based on the environmental information acquired by the information acquisition unit 11 and the ventilation path that is set by the ventilation-path setting unit 141. The output unit 143 is configured to output the ventilation path that is set by the ventilation-path setting unit 141 and the ventilation quantity that is set by the ventilation-quantity setting unit 142. The ventilation-path setting unit 141 is configured to set the plurality of candidate paths based on the environmental information. The plurality of candidate paths have the priorities in descending order of the expected ventilation effects. In the case where the first candidate path having the highest priority of the plurality of candidate paths is identical with the previously set ventilation path, the ventilation-path setting unit 141 is configured to set the first candidate path as the ventilation path, when the difference value (T2−T1) between the room temperature T2 previously acquired by the information acquisition unit 11 and the room temperature T1 presently acquired by the information acquisition unit 11 is equal to or more than the predetermined threshold δ1. On the other hand, in this case, the ventilation-path setting unit 141 is configured to set, as the ventilation path, the second candidate path having the second highest priority of the plurality of candidate paths, when the difference value (T2−T1) is less than the threshold δ1.

The ventilation system includes the ventilation control device 1 and the opening control device 2. The opening control device 2 is configured to control the opening/closing of the opening 81 of the building 8 by the control of the ventilation control device 1.

The program is for, at predetermined intervals, switching to the ventilation path in the building 8 and setting the ventilation quantity of the air passing through the switched ventilation path. The program causes the computer to function as the ventilation-path setting unit 141, a ventilation-quantity setting unit 142, and the output unit 143. The ventilation-path setting unit 141 is configured to set the ventilation path based on the environmental information acquired by the information acquisition unit 11. The environmental information includes the weather information and the indoor environmental information. The weather information includes the wind pertinent information, and the air temperature and the air humidity outside the building 8. The air temperature outside the building 8 is the outside air temperature. The air humidity outside the building 8 is the outside air humidity. The wind pertinent information is information about the wind flowing outside the building 8. The indoor environmental information includes the room temperature and the room humidity in the building 8. The ventilation-path setting unit 141 is configured to set the ventilation path based on the environmental information acquired by the information acquisition unit 11. The ventilation-quantity setting unit 142 is configured to set the ventilation quantity based on the environmental information acquired by the information acquisition unit 11 and the ventilation path that is set by the ventilation-path setting unit 141. The output unit 143 is configured to output the ventilation path that is set by the ventilation-path setting unit 141 and the ventilation quantity that is set by the ventilation-quantity setting unit 142. The program causes the computer, as the ventilation-path setting unit 141, to perform the following operations. The ventilation-path setting unit 141 is configured to set the plurality of candidate paths based on the environmental information. The plurality of candidate paths have the priorities in descending order of the expected ventilation effects. In the case where the first candidate path having the highest priority of the plurality of candidate paths is identical with the previously set ventilation path, the ventilation-path setting unit 141 is configured to set the first candidate path as the ventilation path, when the difference value (T2−T1) between the room temperature T2 previously acquired by the information acquisition unit 11 and the room temperature T1 presently acquired by the information acquisition unit 11 is equal to or more than a predetermined threshold δ1. On the other hand, in this case, the ventilation-path setting unit 141 is configured to set, as the ventilation path, the second candidate path having the second highest priority of the plurality of candidate paths, when the difference value (T2−T1) is less than the threshold δ1.

In the ventilation system according to the present embodiment described above, the ventilation control device 1, when the difference value (T2−T1) between the room temperature T2 previously acquired and the room temperature T1 presently acquired is less than the threshold δ1 while the first candidate path having the highest priority is identical with the previously set ventilation path, the ventilation control device 1 is configured to set, as the ventilation path, not the first candidate path but the second candidate path having the second highest priority. Therefore, in the ventilation control device 1 according to the present embodiment, when the actual ventilation effect is small although the first large candidate path, in which the expected ventilation effect is large, has been previously set as the ventilation path last time, the second path can be presently set as the ventilation path instead of the first candidate path in which the actual ventilation effect is small. As a result, it is possible to precisely set the ventilation path having the actual large ventilation effect. That is, it is possible to confirm the actual ventilation effect and set an appropriate ventilation path. For example, even if there is no information about the detailed room arrangement (including the position of the opening 81) of the building 8, it is possible to confirm the actual ventilation effect and set the appropriate ventilation path.

As in the present embodiment, the ventilation-path setting unit 141 is preferably configured to always set the second candidate path as the ventilation path after the difference value (T2−T1) in the first candidate path is less than the threshold δ1 the predetermined times.

In the ventilation system according to the present embodiment, the ventilation control device 1 is configured to always set, as the ventilation path, the second candidate path having the second highest priority, after the difference value (T2−T1) between the room temperature T2 previously acquired and the room temperature T1 presently acquired in the first candidate path having the highest priority is less than the threshold δ1 the predetermined times. Therefore, in the ventilation control device 1 according to the present embodiment, it is possible to securely exclude the ventilation path in which the actual small ventilation effect is small.

The ventilation-path setting unit 141 is preferably configured to always set the second candidate path as the ventilation path after the difference value (T2−T1) in the first candidate path is less than the threshold δ1 the predetermined times.

In the ventilation system according to the present embodiment, the ventilation control device 1 is configured to control the opening control device 2 configured to control the opening/closing of the opening 81 based on the ventilation path and the ventilation quantity that are output from the output unit 143. Therefore, in the ventilation control device 1 according to the embodiment, since the opening 81 can be made to open/close automatically, it is possible to perform the ventilation compared with the case where the opening 81 is made to open/close manually.

The ventilation control device 1 further includes the state determining unit 145 and the auxiliary-control unit 146. The state determining unit 145 is configured to determine the state of the ventilation auxiliary device 3 according to the ventilation path and the ventilation quantity that are output from the output unit 143. The ventilation auxiliary device 3 is configured to assist the ventilation through the ventilation path. The auxiliary-control unit 146 is configured to control the ventilation auxiliary device 3 so that the ventilation auxiliary device 3 is in the state determined by the state determining unit 145.

In the ventilation control system according to the present embodiment, the ventilation control device 1 is configured to control each ventilation auxiliary device 3, which is configured to assist the ventilation through the ventilation path, according to the ventilation path that is set by the ventilation-path setting unit 141 and the ventilation quantity that is set by the ventilation-quantity setting unit 142. Therefore, in the ventilation control device 1 according to the embodiment, even if the sufficient ventilation is not obtained with the presently set ventilation path, it is possible to operate each ventilation auxiliary device 3 to prompt the ventilation. As a result, it is possible to improve in the comfort by the ventilation even the case of no wind.

Preferably, the ventilation control device 1 further includes the first determining unit 151, the second determining unit 152, the third determining unit 153, and the switching-interval determining unit 154. The first determining unit 151 is configured to determine whether or not the first absolute difference |T1−T3|, which indicates the absolute difference between the room temperature T1 and the outside air temperature T3 that are acquired by the information acquisition unit 11, is less than the first specified value A1. The second determining unit 152 is configured, when the first absolute difference |T1−T3| is less than the first specified value A1, to determine whether or not the second absolute difference |T1−T4|, which indicates the absolute difference between the room temperature T1 acquired by the information acquisition unit 11 and the preset temperature T4 in the ventilation path, is less than the second specified value A2. The third determining unit 153 is configured, when the second absolute difference |T1−T4| is less than the second specified value A2, to determine whether or not the third absolute difference |T1−T2|, which indicates the absolute difference between the room temperature T1 presently acquired by the information acquisition unit 11 and the room temperature T2 previously acquired by the information acquisition unit 11, is less than the third specified value A3. The switching-interval setting unit 154 is configured to set each of the predetermined intervals to the first time period, when the first absolute difference |T1−T3| is equal to or more than the first specified value A1, when the second absolute difference |T1−T4| is equal to or more than the second specified value A2, or when the third absolute difference |T1−T2| is equal to or more than the third specified value A3. On the other hand, the switching-interval setting unit 154 is configured to set each of the predetermined intervals to the second time period longer than the first time period when the third absolute difference |T1−T2| is less than the third specified value A3.

In the ventilation system according to the present embodiment, the ventilation control device 1 is configured to comparatively shorten the switching interval when any of the first absolute difference |T1−T2|, the second absolute difference |T1−T3|, or the third absolute difference |T1−T4| is equal to or more than the specified value (the first to third specified values A1 to A3). On the other hand, the ventilation control device 1 according to the present embodiment is configured to comparatively lengthen the switching interval when all of the first absolute difference |T1−T2|, the second absolute difference |T1−T3|, and the third absolute difference |T1−T4| are less than the specified values A1 to A3. Therefore, in the ventilation control device 1 according to the embodiment, it is possible to perform the ventilation at switching intervals as long as possible while maintaining temperature environment in which one or more persons existing in the building 8 (one or more persons in rooms) do not feel discomfort if necessary. As a result, it is possible to improve energy saving and comfort by the ventilation without giving one or more persons in rooms discomfort by frequent switching.

In the present embodiment, the first acquisition unit 111 of the information acquisition unit 11 is configured to acquire the wind pertinent information from the anemometer 4. However, as a modification of the present embodiment, the first acquisition unit 111 may be configured to acquire the wind pertinent information from an external device (not shown). The external device should just be, for example, a device configured to acquire and hold the wind pertinent information periodically.

In the present embodiment, the second acquisition unit 112 of the information acquisition unit 11 is configured to acquire the outside air temperature and outside air humidity from the first thermo-hygrometer 5 installed outside the building 8. However, as a modification of the present embodiment, the second acquisition unit 112 may be configured to acquire the outside air temperature and outside air humidity from an external device (not shown). The external device should just be, for example, a device configured to acquire the outside air temperature and outside air humidity periodically.

In the present embodiment, the third acquisition unit 113 of the information acquisition unit 11 is configured to acquire the indoor environmental information from the second thermo-hygrometer 6 installed in the building 8. However, as a modification of the present embodiment, the third acquisition unit 113 may be configured to acquire the indoor environmental information from an external device (not shown). The external device may be, for example, a device configured to acquire the indoor environmental information periodically.

As a modification of the present embodiment, the output unit 143 may be configured to output the ventilation state (ventilation path, ventilation quantity) that is presently set not only to the opening control unit 144 and the auxiliary-control unit 146 but also to a report device 9. In the case of the present modification, the report device 9 is configured to report the ventilation state that is output from the output unit 143. Therefore, it is possible to report the presently set ventilation state to one or more persons in rooms. The report device 9 configured to report the ventilation state may be a display device configured to display the ventilation state on a screen thereof, and may be a sound-output device configured to output the ventilation state with a sound. The sound-output device is, for example, a speaker.

In the present embodiment, the opening control unit 144 is configured to control the plurality of opening control devices 2. However, as a modification of the present embodiment, the output unit 143 may be configured to output the ventilation state (ventilation path, ventilation quantity) that is presently set to a management device (not shown) that is configured to manage the plurality of opening control devices 2. In the case of the present modification, if acquiring the ventilation state from the output unit 143, the management device is configured to determine, based on the ventilation state, a control content of each opening control device 2. Then, the management device is configured to control each opening control device 2 according to the control content.

In the present embodiment, the ventilation-quantity setting unit 142 has the function as the timer. However, as a modification of the present embodiment, the configuration of the ventilation control device 1 other than the ventilation-quantity setting unit 142 may have the function as the timer.

Although the present invention has been described with reference to a certain preferred embodiment, numerous modifications and variations can be made by those skilled in the art without departing from the true spirit and scope of this invention, namely claims. 

1. A ventilation control device configured, at predetermined intervals, to switch to a ventilation path in a building and to set a ventilation quantity of air passing through the ventilation path, the ventilation control device comprising: an information acquisition unit configured to acquire environmental information, the environmental information comprising: weather information comprising wind pertinent information about wind flowing outside the building, and air temperature and air humidity outside the building; and indoor environmental information comprising room temperature and room humidity in the building, the air temperature outside the building being an outside air temperature, the air humidity outside the building being an outside air humidity; a ventilation-path setting unit configured to set the ventilation path based on the environmental information acquired by the information acquisition unit; a ventilation-quantity setting unit configured to set the ventilation quantity based on the environmental information acquired by the information acquisition unit and the ventilation path that is set by the ventilation-path setting unit; and an output unit configured to output the ventilation path that is set by the ventilation-path setting unit and the ventilation quantity that is set by the ventilation-quantity setting unit, wherein the ventilation-path setting unit is configured: to set a plurality of candidate paths based on the environmental information, the plurality of candidate paths having priorities in descending order of expected ventilation effects; and in a case where a first candidate path having a highest priority of the plurality of candidate paths is identical with a previously set ventilation path, to set the first candidate path as the ventilation path, when a difference value between a room temperature previously acquired by the information acquisition unit and a room temperature presently acquired by the information acquisition unit is equal to or more than a predetermined threshold, and to set, as the ventilation path, a second candidate path having a second highest priority of the plurality of candidate paths, when the difference value is less than the predetermined threshold.
 2. The ventilation control device according to claim 1, wherein the ventilation-path setting unit is configured to always set the second candidate path as the ventilation path after the difference value in the first candidate path is less than the predetermined threshold predetermined times.
 3. The ventilation control device according to claim 1, further comprising an opening control unit configured to control an opening control device configured to control opening/closing of an opening formed in the building, based on the ventilation path and the ventilation quantity that are output from the output unit.
 4. The ventilation control device according to claim 3, further comprising: a state determining unit configured to determine a state of a ventilation auxiliary device configured to assist ventilation through the ventilation path according to the ventilation path and the ventilation quantity that are output from the output unit; and an auxiliary-control unit configured to control the ventilation auxiliary device so that the ventilation auxiliary device is in the state determined by the state determining unit.
 5. The ventilation control device according to claim 1, further comprising: a first determining unit configured to determine whether or not a first absolute difference, which indicates an absolute difference between the room temperature and the outside air temperature that are acquired by the information acquisition unit, is less than a first specified value; a second determining unit configured, when the first absolute difference is less than the first specified value, to determine whether or not a second absolute difference, which indicates an absolute difference between the room temperature acquired by the information acquisition unit and a preset temperature in the ventilation path, is less than a second specified value; a third determining unit configured, when the second absolute difference is less than the second specified value, to determine whether or not a third absolute difference, which indicates an absolute difference between the room temperature presently acquired by the information acquisition unit and the room temperature previously acquired by the information acquisition unit, is less than a third specified value; and a switching-interval setting unit configured: to set each of the predetermined intervals to a first time period, when the first absolute difference is equal to or more than the first specified value, when the second absolute difference is equal to or more than the second specified value, or when the third absolute difference is equal to or more than the third specified value; and to set each of the predetermined intervals to a second time period longer than the first time period when the third absolute difference is less than the third specified value.
 6. A ventilation system comprising: the ventilation control device according to claim 1; and an opening control device configured to control opening/closing of an opening of the building by control of the ventilation control device.
 7. A computer-readable recording medium recording a program for, at predetermined intervals, switching to a ventilation path in a building and setting a ventilation quantity of air passing through the ventilation path, the program causing a computer to function as: a ventilation-path setting unit configured to set the ventilation path based on environmental information acquired by an information acquisition unit, the environmental information comprising: weather information comprising wind pertinent information about wind flowing outside the building, and air temperature and air humidity outside the building; and indoor environmental information comprising room temperature and room humidity in the building, the air temperature outside the building being an outside air temperature, the air humidity outside the building being an outside air humidity; a ventilation-quantity setting unit configured to set the ventilation quantity based on the environmental information acquired by the information acquisition unit and the ventilation path that is set by the ventilation-path setting unit; and an output unit configured to output the ventilation path that is set by the ventilation-path setting unit and the ventilation quantity that is set by the ventilation-quantity setting unit, wherein the program causes the computer, as the ventilation-path setting unit: to set a plurality of candidate paths based on the environmental information, the plurality of candidate paths having priorities in descending order of expected ventilation effects; and to set, in a case where a first candidate path having a highest priority of the plurality of candidate paths is identical with a previously set ventilation path, the first candidate path as the ventilation path, when a difference value between a room temperature previously acquired by the information acquisition unit and a room temperature presently acquired by the information acquisition unit is equal to or more than a predetermined threshold, and to set, as the ventilation path, a second candidate path having a second highest priority of the plurality of candidate paths, when the difference value is less than the predetermined threshold.
 8. The ventilation control device according to claim 2, further comprising an opening control unit configured to control an opening control device configured to control opening/closing of an opening formed in the building, based on the ventilation path and the ventilation quantity that are output from the output unit.
 9. The ventilation control device according to claim 8, further comprising: a state determining unit configured to determine a state of a ventilation auxiliary device configured to assist ventilation through the ventilation path according to the ventilation path and the ventilation quantity that are output from the output unit; and an auxiliary-control unit configured to control the ventilation auxiliary device so that the ventilation auxiliary device is in the state determined by the state determining unit.
 10. The ventilation control device according to claim 2, further comprising: a first determining unit configured to determine whether or not a first absolute difference, which indicates an absolute difference between the room temperature and the outside air temperature that are acquired by the information acquisition unit, is less than a first specified value; a second determining unit configured, when the first absolute difference is less than the first specified value, to determine whether or not a second absolute difference, which indicates an absolute difference between the room temperature acquired by the information acquisition unit and a preset temperature in the ventilation path, is less than a second specified value; a third determining unit configured, when the second absolute difference is less than the second specified value, to determine whether or not a third absolute difference, which indicates an absolute difference between the room temperature presently acquired by the information acquisition unit and the room temperature previously acquired by the information acquisition unit, is less than a third specified value; and a switching-interval setting unit configured: to set each of the predetermined intervals to a first time period, when the first absolute difference is equal to or more than the first specified value, when the second absolute difference is equal to or more than the second specified value, or when the third absolute difference is equal to or more than the third specified value; and to set each of the predetermined intervals to a second time period longer than the first time period when the third absolute difference is less than the third specified value.
 11. The ventilation control device according to claim 3, further comprising: a first determining unit configured to determine whether or not a first absolute difference, which indicates an absolute difference between the room temperature and the outside air temperature that are acquired by the information acquisition unit, is less than a first specified value; a second determining unit configured, when the first absolute difference is less than the first specified value, to determine whether or not a second absolute difference, which indicates an absolute difference between the room temperature acquired by the information acquisition unit and a preset temperature in the ventilation path, is less than a second specified value; a third determining unit configured, when the second absolute difference is less than the second specified value, to determine whether or not a third absolute difference, which indicates an absolute difference between the room temperature presently acquired by the information acquisition unit and the room temperature previously acquired by the information acquisition unit, is less than a third specified value; and a switching-interval setting unit configured: to set each of the predetermined intervals to a first time period, when the first absolute difference is equal to or more than the first specified value, when the second absolute difference is equal to or more than the second specified value, or when the third absolute difference is equal to or more than the third specified value; and to set each of the predetermined intervals to a second time period longer than the first time period when the third absolute difference is less than the third specified value.
 12. The ventilation control device according to claim 4, further comprising: a first determining unit configured to determine whether or not a first absolute difference, which indicates an absolute difference between the room temperature and the outside air temperature that are acquired by the information acquisition unit, is less than a first specified value; a second determining unit configured, when the first absolute difference is less than the first specified value, to determine whether or not a second absolute difference, which indicates an absolute difference between the room temperature acquired by the information acquisition unit and a preset temperature in the ventilation path, is less than a second specified value; a third determining unit configured, when the second absolute difference is less than the second specified value, to determine whether or not a third absolute difference, which indicates an absolute difference between the room temperature presently acquired by the information acquisition unit and the room temperature previously acquired by the information acquisition unit, is less than a third specified value; and a switching-interval setting unit configured: to set each of the predetermined intervals to a first time period, when the first absolute difference is equal to or more than the first specified value, when the second absolute difference is equal to or more than the second specified value, or when the third absolute difference is equal to or more than the third specified value; and to set each of the predetermined intervals to a second time period longer than the first time period when the third absolute difference is less than the third specified value.
 13. The ventilation control device according to claim 8, further comprising: a first determining unit configured to determine whether or not a first absolute difference, which indicates an absolute difference between the room temperature and the outside air temperature that are acquired by the information acquisition unit, is less than a first specified value; a second determining unit configured, when the first absolute difference is less than the first specified value, to determine whether or not a second absolute difference, which indicates an absolute difference between the room temperature acquired by the information acquisition unit and a preset temperature in the ventilation path, is less than a second specified value; a third determining unit configured, when the second absolute difference is less than the second specified value, to determine whether or not a third absolute difference, which indicates an absolute difference between the room temperature presently acquired by the information acquisition unit and the room temperature previously acquired by the information acquisition unit, is less than a third specified value; and a switching-interval setting unit configured: to set each of the predetermined intervals to a first time period, when the first absolute difference is equal to or more than the first specified value, when the second absolute difference is equal to or more than the second specified value, or when the third absolute difference is equal to or more than the third specified value; and to set each of the predetermined intervals to a second time period longer than the first time period when the third absolute difference is less than the third specified value.
 14. The ventilation control device according to claim 9, further comprising: a first determining unit configured to determine whether or not a first absolute difference, which indicates an absolute difference between the room temperature and the outside air temperature that are acquired by the information acquisition unit, is less than a first specified value; a second determining unit configured, when the first absolute difference is less than the first specified value, to determine whether or not a second absolute difference, which indicates an absolute difference between the room temperature acquired by the information acquisition unit and a preset temperature in the ventilation path, is less than a second specified value; a third determining unit configured, when the second absolute difference is less than the second specified value, to determine whether or not a third absolute difference, which indicates an absolute difference between the room temperature presently acquired by the information acquisition unit and the room temperature previously acquired by the information acquisition unit, is less than a third specified value; and a switching-interval setting unit configured: to set each of the predetermined intervals to a first time period, when the first absolute difference is equal to or more than the first specified value, when the second absolute difference is equal to or more than the second specified value, or when the third absolute difference is equal to or more than the third specified value; and to set each of the predetermined intervals to a second time period longer than the first time period when the third absolute difference is less than the third specified value.
 15. A ventilation system comprising: the ventilation control device according to claim 2; and an opening control device configured to control opening/closing of an opening of the building by control of the ventilation control device.
 16. A ventilation system comprising: the ventilation control device according to claim 3; and the opening control device configured to control opening/closing of the opening of the building by control of the ventilation control device.
 17. A ventilation system comprising: the ventilation control device according to claim 4; and the opening control device configured to control opening/closing of the opening of the building by control of the ventilation control device.
 18. A ventilation system comprising: the ventilation control device according to claim 5; and an opening control device configured to control opening/closing of an opening of the building by control of the ventilation control device.
 19. A ventilation system comprising: the ventilation control device according to claim 8; and an opening control device configured to control opening/closing of an opening of the building by control of the ventilation control device.
 20. A ventilation system comprising: the ventilation control device according to claim 9; and an opening control device configured to control opening/closing of an opening of the building by control of the ventilation control device. 